1. Field of the Invention
This invention relates to a method and apparatus for classifying vehicle occupants utilizing multiple vehicle sensors to generate a three-dimensional profile.
2. Related Art
Most vehicles include airbags and seatbelt restraint systems that work together to protect the driver and passengers from experiencing serious injuries due to high-speed collisions. It is important to control the deployment force of the airbags based on the size of the driver or the passenger. When an adult is seated on the vehicle seat, the airbag should be deployed in a normal manner. If a small child is sitting on the seat, then the airbag should not be deployed or should be deployed at a significantly lower deployment force. One way to control the airbag deployment is to monitor the weight and position of the seat occupant. The weight information and position information can be used to classify seat occupants into various groups, e.g., adult, child, infant, and occupant close to dashboard, etc., to ultimately control the deployment force of the airbag.
There are many different systems for measuring weight and determining the position of a seat occupant. These systems use sensors placed in various locations within the vehicle to continuously monitor the position and weight of the occupants. For example, a typical vehicle may include load cells mounted within the seat to measure occupant weight and optical sensors mounted to the dashboard to determine the position of the occupant. Information from the sensors is compiled by a central processing unit and the occupant is classified. Airbag deployment is then controlled based on this classification.
Current classification systems typically use a decision tree method for assigning a class to an occupant. The decision tree method offers only a limited number of comparison tests, which can lead to classification inaccuracies. Further, the decision tree method is unable to adapt to accommodate changes within the system as the system operates over time.
Another problem with current classification systems is that classification accuracy is affected by the number and orientation of seat sensors. Each vehicle can have a different mounting requirement for seat sensors. Smaller vehicles with small seats and limited packaging space, often cannot accommodate a preferred number of sensors or a preferred sensor mounting orientation, which can result in inaccuracies. Further, each different sensor mounting configuration requires its own software, which increases system cost.
System inaccuracies are also caused by sensor shifting. Over time, sensors within the vehicle can be shifted from their original locations creating offset. Thus, when there is offset, the classification system is classifying occupants assuming that the sensors are still in their original locations while in practice the sensors are providing measurements from other locations.
Thus, it is desirable to have a method and apparatus for classifying seat occupants that can reduce inaccuracies caused by sensor shifting, variable sensor mounting configurations, and limited decision processes. The method and apparatus should also be able to adapt with system changes over time in addition to overcoming the above referenced deficiencies with prior art systems.
The subject invention includes a method and apparatus for classifying vehicle occupants utilizing multiple vehicle sensors to generate a three-dimensional profile.
The classification system utilizes sensors that are installed in various locations throughout the vehicle. The sensors transmit data to a central processing unit that generates a three-dimensional profile representative of the vehicle occupant. Fuzzy logic is used to reduce inaccuracies by providing multiple decision levels for various stages of the classification. The central processing unit also reduces inaccuracies caused by offset by utilizing a measuring function to determine the amount of offset and to generate an appropriate correction factor to provide a more accurate three-dimensional profile. Electrically erasable programmable read-only memory (EEPROM) is used to reduce inaccuracies associated with seat occupant weight sensors that have mounting configurations that vary depending upon the vehicle.
The subject invention provides an improved method and apparatus that more accurately classifies vehicle occupants. The classification information is used for vehicle restraint system control. These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.